I filled some holes in my concrete floor about a week ago. I bought one of these ready to mix bags. The concrete still hasn't gone off though. When I scratch the top of it with my nail, I can scratch some off. What have I done wrong?
Rubbish concrete
- Thread starter Albopalbo
- Start date
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How much water did you put in the mix?
Did you cover the area you repaired with a poly sheet and water down the next day?
If you added too much water to the mix this could have weakened it or if the area underneath the repair was dry and porus this could have also caused suction and the mix to hydrate quickly, it is a good idea to dampen the area before you fill it.
After filling in holes it is best to cover the area with a poly sheet over night then rehydrate the area the following day, this helps to toughen the concrete up.
It can take up to 4 weeks for concrete to get to a good curing strength.
Did you cover the area you repaired with a poly sheet and water down the next day?
If you added too much water to the mix this could have weakened it or if the area underneath the repair was dry and porus this could have also caused suction and the mix to hydrate quickly, it is a good idea to dampen the area before you fill it.
After filling in holes it is best to cover the area with a poly sheet over night then rehydrate the area the following day, this helps to toughen the concrete up.
It can take up to 4 weeks for concrete to get to a good curing strength.
Maybe I did put in too much water. Will I have to remove it and do it again? I still have about an inch to fill, so this 'weak' stuff will be underneath the next layer. I'm going to tile over it by the way. Thanks.
It depends how large the area is you have repaired, but it's not a good method to leave an inch to be topped up, as it may not bond to the layer underneath and eventually pull away and they will be curing at different rates too, should do it all in one hit.
If you have added too much water to the mix, it is likely that it will never cure to a high enough strength.
If you have added too much water to the mix, it is likely that it will never cure to a high enough strength.
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It would definitely be good to know what sort of area & thickness you are talking about. Getting a good bond between the separate 'layers' is crucial. Is this a slab that has been down for several years, or one that has been recently poured? And yes, the amount of water added to the mix is also critical.
The area is about 3 foot long, and 2-3inches deep. There are some more areas that go to about 6 inches deep. The concrete has been down for years in the kitchen floor. The top layer is a damp proof membrane (bitumen?) about 1 inch thick, which has obviously been broken.
A guy on this forum recommended I fill with concrete until 1 inch from the top, bitumen paint it, then fill in the remaining 1 inch?
A guy on this forum recommended I fill with concrete until 1 inch from the top, bitumen paint it, then fill in the remaining 1 inch?
H
hotrod
I doubt the 1" of concrete has bonded to the bitumen - it will not have had a key unless you scarified the surface and besides 1" is not really deep enough for concrete if the area is going to be trafficked imho.
once newly-laid concrete has dried, it stops curing and gaining strength. If you are able, through misting and plastic sheeting, to keep it damp for a couple of weeks, it will get pretty hard and strong. If it dries out overnight, it will just be crumbly. Once it has gone dry, it does no good trying to wet it again.
This is why underground concrete, which usually never dries out, and continues curing for many years, is particularly hard and strong.
This is why underground concrete, which usually never dries out, and continues curing for many years, is particularly hard and strong.
maybe the solution here, would be to mix your repair and add a waterproof admixture to it, then this can be poured level, then when dry, give it a couple of coats of a waterproof sealant for good measure. This should then prevent any damp coming through.
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